An underwater Atlantean outpost survived beneath the ocean, off the Azores. In 1970, Professor Zaroff discovered the survivors and proposed to raise their settlement from the ocean floor. This would have destroyed the Earth. Zaroff died in the attempt due to the Second Doctor's intervention. (TV: The Underwater Menace)

Later, the Dæmon Azal pointed to the destruction of Atlantis as a warning as to what might happen if he considered Earth, a planet that the Dæmons had helped along, a failed experiment. (TV: The Dæmons)